Scientists have always been baffled about the possibility of life outside the Earth. As a result, various space missions have been launched to search the environmental conditions of our neighboring planets. Experts also send explorations deep into our oceans to understand the ideal habitat for hosting life. Just recently, scientists encountered a type of marine microorganism that provided clues in their search.
Evidence from a Weird Type of Bacteria
Lurking deep in the ocean is a mysterious kind of microbe identified as magnetotactic bacteria containing bullet-shaped magnetic crystals inside their cells. The crystals keep them aligned with the magnetic field lines of the Earth. Some animals evolved to possess receptors responsive to the Earth's magnetism, but these bacteria differ because they have literal magnets inside their bodies. Surprisingly, the magnets move with the magnetic lines regardless of whether the bacteria are alive or dead.
Magnetotactic bacteria have gained the interest of researchers since they were discovered in the 1960s for various reasons. First, they play a significant role in the cycle of bioessential nutrients like nitrogen, carbon, and phosphorus. Their well-built interior crystals can also be preserved in the geological record, where they can give information about past microbial ecosystems and magnetic activities. Since magnetofossils have the potential to survive for billions of years, they can give clues in the search for extraterrestrial life. Scientists involved in the alien search can investigate the remains of magnetotactic microbes on other planets, such as Mars.
An Encounter with the Magnetotactic Bacteria
A team of researchers discovered a type of magnetotactic bacteria living in the opening of a hot hydrothermal vent system in the Mariana Trough. Research senior author Yohey Suzuki, an associate professor in Earth and planetary sciences at the University of Tokyo, expressed his surprise when they saw the microbes. The magnetically sensitive bacteria live almost two miles below the surface of the Pacific Ocean. These organisms usually prefer an environment with vertical chemical gradients, and the vent chimneys in the Mariana Trough lack these conditions.
The weird bacteria were encountered by Suzuki and his colleagues during their deep-sea expedition in 2012 using a remotely operated vehicle. The robotic vehicle called HYPER-DOLPHIN descended to a depth of almost 2,800 meters. It was used in studying the hydrothermal vents in the Mariana Trough, a basin in the western Pacific Ocean that stretches up to 800 miles. The magnetotactic bacteria gathered by the research team are related to a group called Nitrospinae, which plays a crucial role in the global carbon and nitrogen cycles.
A scientific controversy had already erupted when magnetic remnants of life were detected in Martian meteorite Allan Hills 84001 in 1984. Previous reports about the meteorite reveal that the fossils of magnetotactic bacteria were preserved for a long time as biosignatures.
On Earth, the ancestor of this microbe appeared 3.5 billion years ago before the major bacterial phyla diverged, leading to the first emergence of life. In other words, these microorganisms can help the experts trace life's origin back to the Precambrian era, the time in history before the complex forms of animals emerged. The deep-sea environment where the bacteria were discovered could be similar to the type of habitat where life first began on Earth. Their discovery could provide clues on how life on Earth started and offer new insights regarding alien life outside our home planet.
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